Feed leg for rock drills



P 1954 G. c. PEARSON FEED LEG FOR ROCK DRILL-S 2 Sheets-Sheet 1 FiledFeb. 15, 1952 @vrlv Sept. 21, 1954 c, PEARSON 2,689,547

FEED LEG FOR ROCK DRILLS Filed Feb. 15, 1952 2 Sheets-Sheet 2 o 40 /a o/a h J2 M. 37 i a l! 8 f3 za 4 4'0 4" 29 9 24 Z Z! .6 d/"E J 5 if 3 I Qx I 9/! 9\ a i S X W c j a ,iwg wlS F flii fi J/ E r I 23 5/ 2? g a I I22 a v 26 l\ .3// Q x /6/ As V\ 4 v ZLJNJJ N 147/ k v INVE TOR. 6&Jr4v 6lava/w Patented Sept. 21, 1954 FEED LEG FOR ROCK DRILLS Gustav C.Pearson, Denver, Cola,

Gardner-Denver Company, poration of Delaware assignor to Quincy, Ill.,a. cor- Application February 15, 1952, Serial No. 271,738

Claims.

My invention relates to improvements in rock drills and is moreparticularly directed to that type of drill commonly referred to as astoper and the improvement deals especially with the means for holdingthe drill to its work.

The main object of the invention is to provide an'extensible feed legfor drills of the type described wherein the length of the leg may beautomatically extended as the drill progresses into the work.

Another object of the invention is to provide a feeding mechanism whichmight eliminate the usual blocking of the drill, decrease the distancebetween the end of the feeding mechanism and the face of the work. Thisis usually done by building a temporary blocking for the feed pistonsufliciently to hold the drill in a proper relation to its Work.

The invention particularly resides in the provision of a feed leg havingan extension including a cylinder within which a piston operates, andthe piston during certain periods of operation controlling movement inone direction of the extension cylinder.

Another object of the invention is toprovide an extensible feed leghaving a plurality ofcylinders, one within the other and a piston withinone, against which pressure impinges to hold the drill to its work, thuseliminating the disadvantages heretofore experienced with pistons ofseveral diameters particularly a variance in the holding pressure forthe drill.

Further objects of the invention will hereinafter appear, and to all ofthese ends the inventionconsists of the features of construction,arrangement of parts, and combination of -elements,substantially ashereinafter fully described and claimed in the specification and shownin the accompanying drawings, in which:

Figure 1 is a vertical sectional view showing a rock drill havingattached thereto the improved feeding mechanism.

Figure 2 is an enlarged sectional view of the feeding mechanism showingthe respective elements in one position of their operation.

Figure 3 is a view similar to Figure 2 but showing the elements of theleg collapsed, prior toany outward movement, and

Figure 4 is a sectional view showing the position assumed by theextensible elements upon reaching the limits of their outward movements.

Briefly the invention presented herein is to provide a feeding means formaintaining a stoper drill in proper relation to itswork without thenecessity of temporaryblocking.

The principal feature of the invention lies in the provision of acollapsible feed leg having ,a main cylinder, an extension cylinder anda piston one within the other, their combined operations being that thedrill is first fed to its Work by movement of the .extension cylinderrelative to the piston and then upon the extension cylinder reachingapproximately the limit of its movement operating fluid is automaticallydirected against the extension cylinder in a reverse direction movingthe same downwardly with respect to the main ylinder and piston untilthe piston assumes its furtherest innermost :position within the exten-8.1.011 cylinder, whereupon the extension cylinder again :m0ves upwardlywith respect to the piston, carrying with it, as a unit, the maincylinder and the drill connected thereto. Thus, it is apparent that{movement of the drill to its work is accomplished solely by expansionof fluid between the adjacent faces of two pistonheads, areas of likediameters, eliminating any variation in the fluid pressure holding thedrill to its work.

Referring to the drawingsindetai'l, the numeral I indicates a stoperdrill "having at its front end a drill steel .2 receiving lblows from areciprocating hammer 3, positioned within the cylinder of the drill.

The rear end of the drill proper carries the usual distributing valveanda backhead l to which the usual water and air connections are made forproper functioning of the drill, the latter being controlled rbyrasuitable throttle valve positioned within thebackhead.

The drill 'I is also provided with an outwardly extending handle :5having at its outer end a manually operated valve .6, controlling theflow of operating pressure fluid active upon certain elemeni fieqf thedrill and feeding mechanism.

'{Ihe backhead .4,.at:the rear of thedrill i, has positionedthereagainst an element ill, the lower edge of which :is receivablewithin a collar 8, all being 151: 1111i netained to the drill by theusual side rods 1 The-collar :8 is internally threaded receiving therein:the end of a cylinder 9 into which projects a depending ring or skirt Hformed upon the .gunderface :of theelement t and provided with passages13.7. The ring I I surrounds a central port 14.0, the purpose of which.will be clearly [apparent as the description proceeds.

.Posibionsdxvriithin the cylinder 9, and for movement longitudinallythereof, is an extension cylinder "l2 having a piston head 13 which maybe of any conventional type. The upperface of the head [3 is providedwith a centrally disposed tubular projection M, while its "lower facehas a downwardly depending skirt I5 having an annular groove I6 adjacenta tapered portion H, the purpose of which will be hereinafter more fullyapparent. From the drawings it will be observed that the lower end ofthe cylinder 9 has fixed therein a bushing II forming a bearing andsupport for the cylinder I2 and at the same time serving as an abutmentlimiting its outward movement relative to the cylinder 9.

The free end of the cylinder I2 has fitted therein a bushing I8.Slidable within the bushing and the extension cylinder'l2 is a piston I9having at its upper end a conventional piston head 23 and at its lowerend a tapered plug or pivot point 2 I.

Here again the piston head 20 is provided with a centrally tubularprojection 22 partially closed by a cap 23 having positioned thereabouta spring clutch ring A for engagement with the tapered portion I1 andannular ring it carried by the piston head I3 of the cylinder I2,frictionally holding the cylinder I2 and piston I9 in a fixed relationto each other.

The tubular projection I4 of the piston head I3, is similarly providedwith a cap 24 having a spring clutch ring B engageable with the innerface of the depending skirt I I for frictionally holding the extensioncylinder I2 in a fixed relation with respect to the cylinder 9.

Positioned within the tubular projection It and extending through thecap 24 is a tubular piston 26 normally held against the lower face ofthe element IE3 by the spring 21. The purpose of this piston is tocontrol the flow of operating fluid from the port 4!! to the cylinders 9and I2. Upon referring to Figures 1 and 3 it will be observed that theunderface of the element II], particularly that portion surrounding theport 48, is engageable by the end face of the tubular piston 26. Whenengaging the element IE3, as shown in Figure 3, operating fiuid isconducted from the port All through the piston 26 to the interior of theextension cylinder I2, moving the same upwardly relative to the pistonI9.

Figure 2 of the drawing shows the cylinder I2 near the limit of itsupward movement relative to the piston head 26, with its end bushing I8slightly spaced therefrom. In such a position the button 3| of the rod3%, operating the tubular piston 26, is in contact with the underface ofthe piston head 2! Continued upward movement of the cylinder I2 willbring its bushing I8 in direct contact with the piston head 20 and atthe same time the tubular piston 25 is held against upward movement withthe cylinder I2, the result being that the end face of the piston 26 iswithdrawn from engagement with the element Ill. With such a relation ofparts fluid is free to pass from the port 40 into the area surrounded bythe depending skirt II and finally through the passages 31 formedtherein to impinge upon the upper face of the piston I3, moving theextension cylinder I2 downwardly of the cylinder 9 and piston I9. At thesame time fluid within the cylinder I2, between the piston heads !3 and20, is forced therefrom through the tubular piston 26 into the cylinder9, where it mingles with that entering'the cylinder 9 through thepassages 31, thus permitting full downward movement of the extensioncylinder I2 with respect to the cylinder 9 and piston head 20. It willbe noted from the drawings that the operation thus described isaccomplished by means of the fact that the upper face of the piston I3,against which pressure fluid is active, is of a larger area than itsunderface.

The tubular piston 26 is provided adjacent its lower end with openings28 and a fixed plug 29 to which is connected a rod 39 extendingapproximately the full length of the extension cylinder I2, through thetubular projection 22 of the piston head 20, and having at its lower enda tapered button 3| adapted to be engaged during certain periods ofoperation by the underface of the piston head 20, maintaining the piston25 immovable and out of contact with the element Iii upon any furtherupward movement of the extension cylinder I2, for the purpose hereinbefore set forth.

From the foregoing description, it is quite apparent that normally theextension cylinder I2 is frictionally maintained inwardly of cylinder 9by the ring B, and likewise the piston I9 is held inwardly of thecylinder I2 by the frictional engagement of the ring A with thedepending skirt I5 carried by the piston I3 of the cylinder I2.

As previously pointed out, the holding handle 5 has at its free end avalve 6 which is in communication, through passageways 32, 33 and 34with the feeding mechanism. The passageways 32, 33 and 34 serve toconvey to the feed leg operating pressure fluid from the supply 35 andthe throttle valve 36.

Let us now assume that a unit such as that i1- lustrated in Figure 1 isready to be placed in operation and it is being held vertically to drilloverhead rock with its pivot point 2I resting upon the ground or asuitable support. In such a position it will be apparent that the drillsteel 2 has not yet contacted the rock to be drilled.

In starting the unit the operator turns the throttle valve 35 permittingoperating fluid, under pressure, to flow from the supply 35 to thedistributing valve of the drill, setting the drill in operation,whereupon blows from the reciprocating hammer 3 will be transmitted tothe steel 2. At the same time, operating fluid will pass from thethrottle valve 36, through a passageway not shown, to a point midway ofthe drill where it enters the passageway 34 communicating withpassageway 33 formed in the backhead 4. From the passageway 33 fluidflows through passageway 32, extending transversely of the element It,leading to the port 49, the latter being surrounded by the end face ofthe tubular piston 26.

From the tubular piston 26 fluid passes out through openings 28 in itslower end and into extension cylinder 52, between the underface of itspiston head I3 and the upper face of head 20 of piston I9. As the volumeof fluid between piston heads I3 and 20 increases the extension cylinderI2 moves upwardly upon the piston I9 carrying with it the cylinder 9 anddrill I until such time as the steel 2 contacts the face of the rock tobe drilled. Further upward movement of the extension cylinder I2 isdetermined by the drilling progress of the steel into the rock.

Upward movement of the extension cylinder I2 is limited by engagement ofits bushing 58 with the underface of the piston head 26*. However, justprior to the extension cylinder I2 reaching the limit of its upwardmovement, the button 3 I, movable therewith, comes in contact with theunderface of the piston 2Q, whereupon, any continued movement of theextension cylinder moves the element III and its port 60 away from theend face of the piston 26. When this action takes place, fluid is thenpermitted to pass from the port All into that area surrounded by theskirt I I, through the passages 31, where it then becomes active uponthe upper face of the piston head I3 and the underface of the elementIt].

Simultaneously with the passage of fluid 5, through thepassages 3-! toengage the upper face of the piston head I3, fluid from the extensioncylinder l2 will pass throughthe tubular piston 26 to the interior ofcylinder 9, mingling with that flowing through the passages 31'. As thevolume of fluid within the cylinder 9 increases and that within theextension cylinder I2 decreases, by reason of the dilference in theirpiston areas, the extension cylinder will be moved downwardly withrespect to the cylinder 9 and piston l-9; Furthermore, due to the factthat neither the volume of fluid nor its pressure active upon theunderface of the element It has varied, thedrill and its steel will bemaintained or held in its correct drilling relation with the rock. Itwill also be observed that by reason of the fact that the pivot point ofthe leg is immovable and the steel has been held in contact with therock the overall length of the leg has neither increased or decreasedduring the downward movement of the extension cylinder l2.

This downward movement of the extension cylinder l2 continues until theunderface of its head l3 comes in contact with the bushing 4| fixed inthe end of cylinder 9. When this relation of elements occurs, fluid fromthe interior of the cylinder 9 passes through the tubular piston 26,port 28 to again impinge upon the underface of the piston head 13, thusagain moving the extension cylinder 12 upwardly of the piston l9, anddue to that fact that fluid between piston head 13 and element It is notcompressible, the drill and steel will move in unison with the extensioncylinder, determined by the penetration of the steel within the rock.

From the foregoing, it is apparent that I have provided common pistonheads l3 and 20, the adjacent faces of which are of the same area,serving to move and maintain the drill and its steel to the work.Heretofore, in units designed for the same purpose it has been common toprovide pistons of different areas the result being that neither thedrill nor the steel is maintained properly against the work, causing areduction in the work produced and a material loss in efliciency of thedrill.

When it is desirable to retractthe steel from the rock, the operatorturns the hand valve 6 of the holding handle so that an escape might beprovided, through port 40, passageways 32, 33 and 34, for fluid activeupon the element of the leg.

It is believed that the foregoing description covers fully andcompletely the important features of my invention and it will be quiteapparent from the accompanying drawings that the drill will bemaintained to its work by a constant and unvarying pressure solely uponthe head 20 of the piston l9 and the adjacent face of the head l3. Theonly time that fluid pressure is active in cylinder 9 is when theextension cylinder 12 moves longitudinally thereof in a downwarddirection.

Unlike feed legs heretofore, the maintaining of the drill to its work isaccomplished by elements of one diameter, thus maintaining a constantpressure upon the drill during its work. Commonly heretofore, whereextension cylinders or additional pistons have been used to feed adrill, such has been accomplished by pistons of varying areas againstwhich the fluid impinges. As an example, fluid may impinge upon thepiston head of a cylinder corresponding to the extension cylinder [2thus serving to hold the drill to its work and then at a later time whenthe piston l2 has assumed the full length of its movement, a secondpiston operates with a reduced area against which the 6, operating fluidimpinges, thus reducing the pressure holding the drill to its work.

From the foregoing description, it is obvious that movement of thecylinder l2 with respect to the piston l9, and the main cylinder 9, isunrestricted when acted upon by fluid pressure. Any pressure that mightaccumulate within the cylinder '9 and the cylinder I2 during themovement of the elements is permitted to escape through suitable portsprovided in the cylinder walls adjacent their ends.

From the foregoing, it is thought that the construction, operation andmany advantages of the herein described invention will be apparent tothose skilled in the art without further description, and it will beunderstood that various changes in the size, shape, proportion and minordetails of construction may be resorted to without departing from thespirit or sacrificing any of the advantages of the invention.

What I claim is:

1. In a drilling mechanism, a rock drill, an expansible fluid operatedfeed leg holding the drill to its work, said leg including a pair ofcylinders one within the other, a ground engaging piston within theinner cylinder, a throttle valve controlling the flow of fluid to one ofthe cylinders for the movement of both relative to the piston, meansreversing the movement of the inner cylinder with respect to the othercylinder and piston, and said means operable when both cylinders assumea predetermined position relative to the piston.

2. In a drilling mechanism, a rock drill, an expansible fluid operatedfeed leg holding the drill to its work, said leg including a pair oftelescopic cylinders, a piston within the inner cylinder supporting theleg and drill, a valve controlling the flow of fluid to the cylindersfor the movement of both relative to the piston, means reversing themovement of one cylinder with respect to the other cylinder and piston,and said means operable when the reversible cylinder assumes a certainposition relative to the piston.

3. In a drilling mechanism, a rock drill, a fluid actuated feed legholding the drill to its work, said leg including a pair of cylindersone within the other, a piston within the inner cylinder supporting theleg and drill, a valve controlling the flow of fluid to the cylindersfor moving both relative to the piston in the same direction atinterrupted intervals, means reversing the movement of one cylinderprior to said intervals, and said means being operable when thereversible cylinder assumes a certain position during its initialmovement relative to the piston.

4. A drilling unit comprising a rock drill and an expansible fluidoperated feed leg holding the drill to its work, said leg having a pairof cylinders one movable within the other, a support engaging pistonwithin one of said cylinders, the inner of said cylinders having twooperative positions relative to the fixed cylinder, a valve admittingfluid to the cylinders for moving the same in unison relative to thepiston in both operative positions of the inner cylinder, meanscontrolled by the inner cylinder for moving the same from one operativeposition to the other, and said means operable upon certain relationshipof the inner cylinder with the piston.

5. In a drilling unit, the combination of a rock drill and a fluidactuated feed leg holding the drill to its work, said leg including acylinder fixed to the drill, an extension cylinder movable relative tothe fixed cylinder and serving to move tive to the piston, meansreversing the flow of fluid active upon the extension cylinder movingthe same from the inner to the outer extremity of the fixed cylinder,and said means operable when the extension cylinder assumes a certainposition relative to the piston.

6. In a drilling unit, the combination of a rock drill and a fluidactuated feed leg holding the drill to its work, said leg including acylinder fixed to the drill, an extension cylinder movable within thefixed cylinder, a piston head formed on the inner end of the extensioncylinder and movable from one end to the other of the fixed cylinder, asupport engaging piston within the extension cylinder, a valve admittingfluid to the extension cylinder and against the underface of its pistonhead for moving the extension cylinder and drill relative to thesupporting piston, means directing the flow of fluid to the upper faceof the piston head for moving the extension cylinder in a reversedirection relative to the supporting piston, and said means operablewhen the extension cylinder assumes a certain position in its upwardmovement relative to the supporting piston.

'7. In a drilling mechanism, a rock drill, a feed leg holding the drillto its work, said leg having a cylinder fixed to the drill, an extensioncylinder within the fixed cylinder capable of assuming two operativepositions therein, an abutment engaging piston within the extensioncylinder, a valve admitting operating fluid to the extension cylindermoving the same relative to the piston, means carried by the extensioncylinder reversing its direction of movement relative to the piston andfixed cylinder, and said means being operable upon the extensioncylinder reaching a certain position during its first movement.

8. In a drilling unit comprising a rock drill and a fluid pressureactuated feed leg serving to hold the drill to its work, said legincluding a cylinder fixed to the drill, an extension cylinder movablewithin the fixed cylinder, a ground engaging piston within the extensioncylinder, a piston head formed on the extension cylinder and assumingtwo functioning positions within the fixed cylinder, a throttle valveadmitting fluid pressure between the two pistons for moving the drill toits work, and said pistons having like fluid pressure areas whereby thedrill is uniformly held to its work at all times.

9. In a drilling mechanism, a rock drill, fluid actuated means holdingthe drill to its work, said means including a cylinder fixed to thedrill, an abutment engaging element, a second cylinder movable relativeto the first cylinder and element, a valve admitting fluid between thecylinders and element for moving the cylinders away from the element,and means controlled by the element whereby fluid moves the secondcylinder reversely of the first cylinder and element prior to furthermovement of both cylinders relative to the element.

10. In a drilling mechanism, a rock drill, fluid actuated means holdingthe drill to its work, said means including a cylinder fixed to thedrill, a cylinder movable relative to the fixed cylinder and capable ofassuming two functioning positions with respect thereto, an immovableelement over which the second cylinder is movable, a valve admittingfluid pressure to the cylinders moving both relative to the element fromeach assumed position of the second cylinder, and means controlled bythe element regulating the flow of fluid moving the second cylinder fromone functioning position to the other.

References Cited in the file of this patent UNITED STATES PATENTS GartinSept. 22, 1942

